qtrleenc.c 14.2 KB
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/*
 * Quicktime Animation (RLE) Video Encoder
 * Copyright (C) 2007 Clemens Fruhwirth
 * Copyright (C) 2007 Alexis Ballier
 *
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 * This file is based on flashsvenc.c.
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 *
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 * This file is part of FFmpeg.
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 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
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 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

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#include "libavutil/imgutils.h"
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#include "avcodec.h"
#include "bytestream.h"
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#include "internal.h"
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/** Maximum RLE code for bulk copy */
#define MAX_RLE_BULK   127
/** Maximum RLE code for repeat */
#define MAX_RLE_REPEAT 128
/** Maximum RLE code for skip */
#define MAX_RLE_SKIP   254

typedef struct QtrleEncContext {
    AVCodecContext *avctx;
    int pixel_size;
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    AVFrame *previous_frame;
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    unsigned int max_buf_size;
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    int logical_width;
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    /**
     * This array will contain at ith position the value of the best RLE code
     * if the line started at pixel i
     * There can be 3 values :
     * skip (0)     : skip as much as possible pixels because they are equal to the
     *                previous frame ones
     * repeat (<-1) : repeat that pixel -rle_code times, still as much as
     *                possible
     * copy (>0)    : copy the raw next rle_code pixels */
    signed char *rlecode_table;
    /**
     * This array will contain the length of the best rle encoding of the line
     * starting at ith pixel */
    int *length_table;
    /**
     * Will contain at ith position the number of consecutive pixels equal to the previous
     * frame starting from pixel i */
    uint8_t* skip_table;
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    /** Encoded frame is a key frame */
    int key_frame;
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} QtrleEncContext;

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static av_cold int qtrle_encode_end(AVCodecContext *avctx)
{
    QtrleEncContext *s = avctx->priv_data;

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    av_frame_free(&s->previous_frame);
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    av_free(s->rlecode_table);
    av_free(s->length_table);
    av_free(s->skip_table);
    return 0;
}

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static av_cold int qtrle_encode_init(AVCodecContext *avctx)
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{
    QtrleEncContext *s = avctx->priv_data;

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    if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
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        return AVERROR(EINVAL);
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    }
    s->avctx=avctx;
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    s->logical_width=avctx->width;
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    switch (avctx->pix_fmt) {
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    case AV_PIX_FMT_GRAY8:
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        if (avctx->width % 4) {
            av_log(avctx, AV_LOG_ERROR, "Width not being a multiple of 4 is not supported\n");
            return AVERROR(EINVAL);
        }
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        s->logical_width = avctx->width / 4;
        s->pixel_size = 4;
        break;
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    case AV_PIX_FMT_RGB555BE:
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        s->pixel_size = 2;
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        break;
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    case AV_PIX_FMT_RGB24:
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        s->pixel_size = 3;
        break;
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    case AV_PIX_FMT_ARGB:
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        s->pixel_size = 4;
        break;
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    default:
        av_log(avctx, AV_LOG_ERROR, "Unsupported colorspace.\n");
        break;
    }
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    avctx->bits_per_coded_sample = avctx->pix_fmt == AV_PIX_FMT_GRAY8 ? 40 : s->pixel_size*8;
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    s->rlecode_table = av_mallocz(s->logical_width);
    s->skip_table    = av_mallocz(s->logical_width);
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    s->length_table  = av_mallocz_array(s->logical_width + 1, sizeof(int));
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    if (!s->skip_table || !s->length_table || !s->rlecode_table) {
        av_log(avctx, AV_LOG_ERROR, "Error allocating memory.\n");
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        return AVERROR(ENOMEM);
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    }
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    s->previous_frame = av_frame_alloc();
    if (!s->previous_frame) {
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        av_log(avctx, AV_LOG_ERROR, "Error allocating picture\n");
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        return AVERROR(ENOMEM);
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    }

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    s->max_buf_size = s->logical_width*s->avctx->height*s->pixel_size*2 /* image base material */
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                      + 15                                            /* header + footer */
                      + s->avctx->height*2                            /* skip code+rle end */
                      + s->logical_width/MAX_RLE_BULK + 1             /* rle codes */;
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    return 0;
}

/**
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 * Compute the best RLE sequence for a line
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 */
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static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, uint8_t **buf)
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{
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    int width=s->logical_width;
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    int i;
    signed char rlecode;

    /* This will be the number of pixels equal to the preivous frame one's
     * starting from the ith pixel */
    unsigned int skipcount;
    /* This will be the number of consecutive equal pixels in the current
     * frame, starting from the ith one also */
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    unsigned int av_uninit(repeatcount);
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    /* The cost of the three different possibilities */
    int total_skip_cost;
    int total_repeat_cost;

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    int base_bulk_cost;
    int lowest_bulk_cost;
    int lowest_bulk_cost_index;
    int sec_lowest_bulk_cost;
    int sec_lowest_bulk_cost_index;
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    uint8_t *this_line = p->               data[0] + line*p->               linesize[0] +
        (width - 1)*s->pixel_size;
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    uint8_t *prev_line = s->previous_frame->data[0] + line * s->previous_frame->linesize[0] +
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        (width - 1)*s->pixel_size;
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    s->length_table[width] = 0;
    skipcount = 0;

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    /* Initial values */
    lowest_bulk_cost = INT_MAX / 2;
    lowest_bulk_cost_index = width;
    sec_lowest_bulk_cost = INT_MAX / 2;
    sec_lowest_bulk_cost_index = width;

    base_bulk_cost = 1 + s->pixel_size;

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    for (i = width - 1; i >= 0; i--) {

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        int prev_bulk_cost;

        /* If our lowest bulk cost index is too far away, replace it
         * with the next lowest bulk cost */
        if (FFMIN(width, i + MAX_RLE_BULK) < lowest_bulk_cost_index) {
            lowest_bulk_cost = sec_lowest_bulk_cost;
            lowest_bulk_cost_index = sec_lowest_bulk_cost_index;

            sec_lowest_bulk_cost = INT_MAX / 2;
            sec_lowest_bulk_cost_index = width;
        }

        /* Deal with the first pixel's bulk cost */
        if (!i) {
            base_bulk_cost++;
            lowest_bulk_cost++;
            sec_lowest_bulk_cost++;
        }

        /* Look at the bulk cost of the previous loop and see if it is
         * a new lower bulk cost */
        prev_bulk_cost = s->length_table[i + 1] + base_bulk_cost;
        if (prev_bulk_cost <= sec_lowest_bulk_cost) {
            /* If it's lower than the 2nd lowest, then it may be lower
             * than the lowest */
            if (prev_bulk_cost <= lowest_bulk_cost) {

                /* If we have found a new lowest bulk cost,
                 * then the 2nd lowest bulk cost is now farther than the
                 * lowest bulk cost, and will never be used */
                sec_lowest_bulk_cost = INT_MAX / 2;

                lowest_bulk_cost = prev_bulk_cost;
                lowest_bulk_cost_index = i + 1;
            } else {
                /* Then it must be the 2nd lowest bulk cost */
                sec_lowest_bulk_cost = prev_bulk_cost;
                sec_lowest_bulk_cost_index = i + 1;
            }
        }

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        if (!s->key_frame && !memcmp(this_line, prev_line, s->pixel_size))
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            skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
        else
            skipcount = 0;

        total_skip_cost  = s->length_table[i + skipcount] + 2;
        s->skip_table[i] = skipcount;


        if (i < width - 1 && !memcmp(this_line, this_line + s->pixel_size, s->pixel_size))
            repeatcount = FFMIN(repeatcount + 1, MAX_RLE_REPEAT);
        else
            repeatcount = 1;

        total_repeat_cost = s->length_table[i + repeatcount] + 1 + s->pixel_size;

        /* skip code is free for the first pixel, it costs one byte for repeat and bulk copy
         * so let's make it aware */
        if (i == 0) {
            total_skip_cost--;
            total_repeat_cost++;
        }

        if (repeatcount > 1 && (skipcount == 0 || total_repeat_cost < total_skip_cost)) {
            /* repeat is the best */
            s->length_table[i]  = total_repeat_cost;
            s->rlecode_table[i] = -repeatcount;
        }
        else if (skipcount > 0) {
            /* skip is the best choice here */
            s->length_table[i]  = total_skip_cost;
            s->rlecode_table[i] = 0;
        }
        else {
            /* We cannot do neither skip nor repeat
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             * thus we use the best bulk copy  */
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            s->length_table[i]  = lowest_bulk_cost;
            s->rlecode_table[i] = lowest_bulk_cost_index - i;
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        }

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        /* These bulk costs increase every iteration */
        lowest_bulk_cost += s->pixel_size;
        sec_lowest_bulk_cost += s->pixel_size;

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        this_line -= s->pixel_size;
        prev_line -= s->pixel_size;
    }

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    /* Good ! Now we have the best sequence for this line, let's output it */
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    /* We do a special case for the first pixel so that we avoid testing it in
     * the whole loop */

    i=0;
    this_line = p->               data[0] + line*p->linesize[0];

    if (s->rlecode_table[0] == 0) {
        bytestream_put_byte(buf, s->skip_table[0] + 1);
        i += s->skip_table[0];
    }
    else bytestream_put_byte(buf, 1);


    while (i < width) {
        rlecode = s->rlecode_table[i];
        bytestream_put_byte(buf, rlecode);
        if (rlecode == 0) {
            /* Write a skip sequence */
            bytestream_put_byte(buf, s->skip_table[i] + 1);
            i += s->skip_table[i];
        }
        else if (rlecode > 0) {
            /* bulk copy */
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            if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
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                int j;
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                // QT grayscale colorspace has 0=white and 255=black, we will
                // ignore the palette that is included in the AVFrame because
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                // AV_PIX_FMT_GRAY8 has defined color mapping
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                for (j = 0; j < rlecode*s->pixel_size; ++j)
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                    bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
            } else {
                bytestream_put_buffer(buf, this_line + i*s->pixel_size, rlecode*s->pixel_size);
            }
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            i += rlecode;
        }
        else {
            /* repeat the bits */
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            if (s->avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
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                int j;
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                // QT grayscale colorspace has 0=white and 255=black, ...
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                for (j = 0; j < s->pixel_size; ++j)
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                    bytestream_put_byte(buf, *(this_line + i*s->pixel_size + j) ^ 0xff);
            } else {
                bytestream_put_buffer(buf, this_line + i*s->pixel_size, s->pixel_size);
            }
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            i -= rlecode;
        }
    }
    bytestream_put_byte(buf, -1); // end RLE line
}

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/** Encode frame including header */
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static int encode_frame(QtrleEncContext *s, const AVFrame *p, uint8_t *buf)
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{
    int i;
    int start_line = 0;
    int end_line = s->avctx->height;
    uint8_t *orig_buf = buf;

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    if (!s->key_frame) {
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        unsigned line_size = s->logical_width * s->pixel_size;
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        for (start_line = 0; start_line < s->avctx->height; start_line++)
            if (memcmp(p->data[0] + start_line*p->linesize[0],
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                       s->previous_frame->data[0] + start_line * s->previous_frame->linesize[0],
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                       line_size))
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                break;

        for (end_line=s->avctx->height; end_line > start_line; end_line--)
            if (memcmp(p->data[0] + (end_line - 1)*p->linesize[0],
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                       s->previous_frame->data[0] + (end_line - 1) * s->previous_frame->linesize[0],
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                       line_size))
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                break;
    }

    bytestream_put_be32(&buf, 0);                         // CHUNK SIZE, patched later

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    if ((start_line == 0 && end_line == s->avctx->height) || start_line == s->avctx->height)
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        bytestream_put_be16(&buf, 0);                     // header
    else {
        bytestream_put_be16(&buf, 8);                     // header
        bytestream_put_be16(&buf, start_line);            // starting line
        bytestream_put_be16(&buf, 0);                     // unknown
        bytestream_put_be16(&buf, end_line - start_line); // lines to update
        bytestream_put_be16(&buf, 0);                     // unknown
    }
    for (i = start_line; i < end_line; i++)
        qtrle_encode_line(s, p, i, &buf);

    bytestream_put_byte(&buf, 0);                         // zero skip code = frame finished
    AV_WB32(orig_buf, buf - orig_buf);                    // patch the chunk size
    return buf - orig_buf;
}

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static int qtrle_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                              const AVFrame *pict, int *got_packet)
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{
    QtrleEncContext * const s = avctx->priv_data;
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    enum AVPictureType pict_type;
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    int ret;
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    if ((ret = ff_alloc_packet2(avctx, pkt, s->max_buf_size, 0)) < 0)
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        return ret;
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    if (avctx->gop_size == 0 || (s->avctx->frame_number % avctx->gop_size) == 0) {
        /* I-Frame */
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        pict_type = AV_PICTURE_TYPE_I;
        s->key_frame = 1;
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    } else {
        /* P-Frame */
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        pict_type = AV_PICTURE_TYPE_P;
        s->key_frame = 0;
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    }

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    pkt->size = encode_frame(s, pict, pkt->data);
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    /* save the current frame */
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    av_frame_unref(s->previous_frame);
    ret = av_frame_ref(s->previous_frame, pict);
    if (ret < 0) {
        av_log(avctx, AV_LOG_ERROR, "cannot add reference\n");
        return ret;
    }
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#if FF_API_CODED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
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    avctx->coded_frame->key_frame = s->key_frame;
    avctx->coded_frame->pict_type = pict_type;
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FF_ENABLE_DEPRECATION_WARNINGS
#endif
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    if (s->key_frame)
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        pkt->flags |= AV_PKT_FLAG_KEY;
    *got_packet = 1;

    return 0;
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}

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AVCodec ff_qtrle_encoder = {
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    .name           = "qtrle",
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    .long_name      = NULL_IF_CONFIG_SMALL("QuickTime Animation (RLE) video"),
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    .type           = AVMEDIA_TYPE_VIDEO,
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    .id             = AV_CODEC_ID_QTRLE,
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    .priv_data_size = sizeof(QtrleEncContext),
    .init           = qtrle_encode_init,
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    .encode2        = qtrle_encode_frame,
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    .close          = qtrle_encode_end,
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    .pix_fmts       = (const enum AVPixelFormat[]){
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        AV_PIX_FMT_RGB24, AV_PIX_FMT_RGB555BE, AV_PIX_FMT_ARGB, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE
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    },
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};